Power unit



J. G. i-lAwLEY POWER UNIT June 13, 1944.

Filed May 24, 1940 2 Sheets-Sheet 1 gite-sse GHwZfg? `Fune 13, 194%. .1. G. HAwLl-:Y 351,040

POWER UNIT Filed May 24, 1940 2 Sheets-Sheet 2 .Il Ilmm- 75 f1 Y 1\ Mmmgrime/1MM Patented June 13, 1944 umrsn STATES PATENT" OFFICE 2,351,040 lOWEB. UNIT Jesse G. Hawley, Painted Post, N. Y. Application May 24, 1940, Serial No. 337,102

6 Claims.

This invention relates to the art of power units, and more particularly to hydraulically operated devices for imparting motive power.

While many devices have been developed for actuating moving parts, these have generally been adapted for operating some particular type of mechanism and have lackedgeneral utility as a power unit. Furthermore, most such devices, which possess any degree of lnterchangeability, have generally been of complicated construction. and this is particularly true of the duid-operated devices.

I have found that it is possible to produce a simple and inexpensive power unit of general utility and to operate itselectively by hydraulic or mechanical means.

It is therefore an object of this invention to provide a. new and improved power unit.

It is another object to provide a hydraulically operated power unit.

It is a further object to provide a power unit which may be operated either hydraulically or mechanically.

It is an additional object to provide a sealed power unit.

It is also an objectto provide a simple and inexpensive power unlt of general utility.

It is a special object to provide a power unit for actuating braking devices.

With the above and other objects in view, which will be apparent as the description proceeds, I have set forth my invention in the following specication and have illustrated it in the accompanying drawings, in which:

Figure l is a side elevation of the power unit, shown in conjunction with a brake shoe that is shown in section;

Fig. 2 is a horizontal transverse section on the line 2-2 of Fig. 1;

Fig. 3 is a transverse section on the line 3-3 of Fig. 2;

. Fig. 4 is an end elevation of Fig. 2 as viewed from the left;

Fig. 5 is a transverse section on line 5-5 of Fig.2;

Fig. 6 is a detailed View of a modified form of plunger;

Fig; 7 is a vertical elevation of a brake with a slightly modified form of power unit attached thereto that is particularly adapted for-use 'on rear wheels with a hand brake, such as an emergency brake, connected thereto;

Fig. 8 is a horizontal section on the line 8--8 of Fig. '1; and

Fig. 9 is a vertical section on the line 9-9 of Fig. 7.

Referring to the accompanying drawings, and particularly to Figs. 1-5 thereof, my improved power unit 20 preferably comprises a uid cylinder 2|. a piston cylinder 22, a resilient seal 23, a piston 24, and a piston rod 25.

As best shown in Fig. 2, iiuid cylinder 2| and piston cylinder 22 are cup-shaped members terminating in circumferential flanges 26 and 2l, respectively, between which a, flange 28 on the rubber seal 23 and a spacer ring 30 are securely held by a clamping ring 3|, which is securely clamped therearound by any convenient means, as a power press (not shown).

Resilient seal 23 is preformed and is resistant to oils. It is made of any suitable material, such as neoprene, buna rubber, or thiokol. As shown, it comprises a bottom portion 32 which is flat, side wall 33 at right angles thereto, and the aforementioned flange 28 which extends. at right angles to the side wall 33 and terminates in a secondary flange 34 that is parallel to the side wall 33 but spaced therefrom.

'I'he piston 24 comprises a head 35 and a circumferential ange 36 at right anglesthereto. The head 35 and flange 36 are made just sufliciently smaller than the resilient seal 23 to permit the piston 24 to be inserted ln the resilient seal without deforming it, and the internal diameter of the spacer ring 30 is only sumciently larger than the diameter of the piston 24 to permit its moving freely therethrough.

Piston cylinder 22 comprises a bottom portion 3l, which is nat but is provided with an orice 38,-for a purpose to be described later, and a side wall 40, whose internal diameter is equal tothe internal diameter of the side wall 33 of resilient seal 23, and which is only suinciently larger than the external ydiameter of the flange 36 on piston 24 to permit it to move freely. therethrough. Side w'all 40 terminates in the ange 2l described above, and this, in turn, is provided with a right angular extension 4|, which is parallel to the side wall 40 and of a suitable internal diameter such that it just accommodates spacer ring 30 and ange 34 of resilient seal 23.

Fluid cylinder 2| comprises a bottom portion 42 provided with a side wall 43 that is of just suicient internal diameter to allow the 'side wall 33 of resilient seal 23 to t therein without deformation. This construction in conjunction with the closely :fitting circumferential flange 36 of piston 24 prevents lateral pressure on the side wall 33 of the resilient seal 23. Side wall 43 terminates in flange 26 discussed above.

Bottom portion 42 is provided with two bosses 50, 54 that are preferably formed integral therewith. Boss is internally threaded at 5| to receive any suitable coupling (not shown), and is provided with an orifice 52 to permit fluid (not shown) to enter a chamber 53 formed in fluid cylinder 2| between its bottom portion 42 and the resilient seal 23. Boss 54 is preferably internally threaded to receive a correspondingly threaded bleeder plug 55, provided with a square head 58. Bleeder plug 55 communicates with the exterior through a longitudinal orince (not shown) that communicates with a transverse orilice 51, in a shank 58 of reduced diameter. Orince 51 can communicate with a transverse oriflce 68 and thence with the chamber. 53 when the bleeder plug 55 is partially unscrewed from its seat 6|. This may conveniently be done with a screw driver by inserting the latter in a transverse slot 62 in the head of the bleee r plug 55. A

Piston rod 25 is provided with a flat head 18 and a stem 1|. The latter preferably has a detachable plunger 12 which terminates in a tapered head 13, for a purpose to be described later, and with a shank 1.4 of reduced diameter that is telescopeddnto the end of stem 1| and retained therein by a removable pin 15.

Piston rod 25 operates in and is guided by a power head 16 that has a longitudinal aperture 11 of just sufilciently larger internal diameterv than stem 1| and plunger 12 of piston rod 25 to allow these to move therein without undue friction. Power head 18 is preferably a screw machine part that is externally threadedv at 18 to receive two locknuts 38, 8|, to retain the piston cylinder 22 properly spaced from the mechanism which the power unit is intended to operate.

The travel =of piston rod 25 is preferably controlled by a spacer 84, provided with an external flange 85, whose external diameter corresponds to the internal diameter of the side wall 48 of piston cylinder 22, and with an orifice 86 that is of large enough diameter to permit the stem 1| of piston rod 25 to move therethrough without undue friction. A spacer sleeve 81, that is of sufficiently smaller external diameter to fit snugly in spacer 84, and of larger internal diameter than the orifice 36, is designed to retain a stop pin 88, carried by the stem 1| of piston rod 25 but projecting therebeyond, so as to limit the travel of the piston rod 25 between the spacer 84 and the inner end of power head 16. Spacer sleeve 81 is preferably separate from the thread' ed portion 18 of power `head 16. Spacer 84 is also internally threaded to engage end 18 of power head 16.

A heavy coil spring 88 vis telescoped around spacer 84, and bears against the ange 85 therethe inner threaded in bottom portion 42 of fluid cylinder 2|,

of and against the head 18 of piston rod 25, to Y normally force the latter into engagement with piston 24 and cause that to bear against resilient bottom portion 32 of resilient seal 23, but

spring 98 is of insuflicient power to stretch the resilient seal. The latter is free of either compression or distention when it is in normal posilon.

An important use of my invention is to operate vehicle brakes, and I have therefore illustrated such a use in Figs. 1 5. In these, as best shown in Figs. 1-3, the brake comprises brake shoes |88, |8|, a backing plate 82, and a retaining spring |83. The ends of brake shoes |88, i8| are preferably recessed at |84 vto receive` the power head 16,v and at |85 to receive hardened steel inserts |86 for a purpose to be described hereinafter.

Power head 16 is locked into the backing plate |82 by a key |81, and lock nut 8| is drawn up against backing plate |82 to hold the latter tightly against a shoulder |88 on the power head. The latter is preferably provided with a recessed p0rtion ||8 to receive ilange portions on the brake shoes |88. |8|.

When fluid enters chamber 53 in fluid cylinder 2| through the orifice 52. it bears against the bottom portion 32 of resilient seal 23 and moves piston 24 and piston rod 25 forward, against the pressure of spring 98. This causes the tapered head 13 of the plunger 12 to spread apart two steel balls ||2 which, in turn, bear against the hardened steel inserts |86, and thus spread the ends of the brake shoes |88, |8| apart to apply the brake. Steel balls I2 are housed in a transverse recess ||3 in power head 16, and the recesses |84 in the ends of the brake shoes are of `just sufilcient size to receive the head of power head 16 and the steel balls ||2 in the desired inactive position of the brake shoes, which is normally maintained with the aid of spring |83.

It will be obvious that the amount of braking power for a given movement of the piston rod is determined by the angle of the tapered head 13 on plunger 12. In the form shown in Fig. 2, the sides of the tapered head 13 each preferably make approximately a'20 degree angle with the axis of the piston rod 25. Such a construction produces a softer and lower pedal and more braking power with a given movement of the piston rod 25.

In Fig. 6, I have shown a modified form of plunger 12', with a tapered head 13' and a reduced diameter shank 14'. The sides of the tapered head 13' each make a greater angle with the axis of the piston rod, as for example, 30 degrees. This gives a harder and higher pedal and less braking power with the same brake applying pressure. By merely removing the pin 15. plunger 1.2' may be substituted for plunger 12. Similarly, the angle formed by the sides of the tapered head may be made any desired one to give any desired relation between power and given brake applying pressure.

In Figs. 7, 8, and 9, I have shown a slightly modified power unit 28', nearly all of the partsof which are the same as the parts of the power unit 28 shown in` Figs.. 1-5. However, the stem 1|', shown in Figs. 8 and 9, diiers from the stem 1|, shown in Fig. 2, by terminating in a tapered head |28, and the plunger 12" differs fromplunger 12 in that it has no projecting shank'14 and is provided with a circular recess |2|, to receive a hardened steel ball |22 that is interposed between plunger 12" and the tapered head |28 on stem 1|'. As shown in Figs. 8 and 9, the tapered head |28 is flat, or slightly recessed, at its forward end for engagement with the hardened steel ball |22.

Another change comprises the provision of a sleeve |23 that is interposed between lock nut 8|' and the .backing plate |82'. Sleeve |23 is provided with a lateral aperture |24, registering with an aperture |28 in power head 16'. Sleeve |23 also has a guide flange |25 for a diagonallyheaded operating rod |26, that* is adapted to bear against steel ball |22 and force it forward, thus propelling plunger 12" independently of any hydraulic actuation and causing it to apply the brake when its tapered head 13" engages steel balls H2. Operating rod |25 is bifurcated at |21 to receive an operating lever |28, which is preferably pivoted at |38 to the backing plate |82 of the brake. At its opposite end, operating lever |28 is pivotally connected at |3| to an 0perating rod |32 forming part of the emergency brake. The latter is preferably provided with a coil spring |33 that normally bears against operating rod |32 to maintain the emergency brake sultant total loss of braking power.

in the o position. 'Ihe emergency brake is applied by pulling the operating cable I 34 in the usual way.

From the above description, it will be seen that I my new power -unit is of simple and inexpensive construction and comprises a minimum of parts. Furthermore, since the power unit is sealed at the time it is made, it will thereafter continue to remain free from dirt and grit, which is one of the common causes for failure of conventional types of piston, cup and cylinder hydraulic mechanisms.

Among the other outstanding advantages of my new power unit is the fact that it is mounted outside of the brake cavity. This prevents the unit from getting gas-lock, which often happens with prior constructions because the heat developed by the brakes gasiiies the fluid with a re- Furthermore, while my improved power unit is so designed that it is not believed any iiuid can leak by the resilient seal, nevertheless, if a leak should occur for any reason, it would not aifect the brake inasmuch as the fluid would drop outside of the brake cavity and would not touch the brake lining. l .y

A further highlyimportant advantage of my new power unit is that it could be replaced, should this ever become necessary, without even removing a wheel from the vehicle, since it can be unscrewed from the outside.

Although I have herein disclosed my power unit as being adapted for the operationof brakes, it will be obvious that it may be used for many other purposes, such as the operation of the flaps of an airplane orautogiro, and for any other device to which it is desired to transmit motive power.

It will therefore be apparent that I have developed a new and highly useful power unit which is capable of general application and may be operated selectively, either hydraulically or mechanically.

As many apparently widely different embodiments of this invention may be made without departing from the spirit thereof, it is understood that I do not limit myself to the foregoing` embodiments or description except as indicated in the following claims.

I claim:

1. A self-contained power unit comprising a. iiuid cylinder, a piston cylinder, a resilient seal interposed between these two cylinders and comprising a bottom portion whose area is equal to the internal cross-section of the iiuid cylinder, a continuous side wall in contact with the inner wall of the fluid cylinder, and a projecting flange for clamping between adjacent portions of the uid cylinder and piston cylinder, and a piston actuated -by movements oi' the resilient seal, the piston comprising an end portion and a continuous sidawall, the latter fitting snugly within the side wall of the resilient seal and the bottom portion of the piston conforming to and sup-v porting the bottom portion of the resilient seal, the piston also having a piston rod with a tapered end projecting beyond the piston cylinder a continuous side wall in contact with the inner wall of theiiuid cylinder, and a projecting flange for clamping between adjacent portions of the fluid cylinder and piston cylinder, and a piston actuated by movements of the resilient'seal, the piston comprising an end portion and a continuous side wall, the latter fitting snugly within the side wall of the resilientseal and the bottom portion of the piston-conforming to and supporting the bottom portion yof the resilient seal,

the piston also having a piston rod with a tapered end projecting beyond the piston cylinder, a pairof thrust-imparting metal balls actuated by said tapered end, and means for limiting the travel of the piston.

3. A self-contained power unit comprising a uid cylinder, a piston cylinder, a resilient seal interposed between these two cylinders and comprising a bottom portion whose area is equal to the internal cross-section of the fluid cylinder,

a continuous side wall in contact with the inner wall of the fluid cylinder, and a projecting flange for clamping between adjacent portions of the fluid cylinder and piston cylinder, and a piston actuated by movements of the resilient seal, the

piston comprising an end portion and a continuous side wall, the latter fitting snugly within the side wall of the resilient seal and the bottom portion of the piston conforming to and supporting the bottom portion of the resilient seal, the piston also having a piston rod with a tapered end projecting beyond the piston cylinder, a pair of thrust-imparting metal balls actuated by said tapered end. and means for changing the thrust imparted by the tapered end for a given movement of the piston.

4. A self-contained power unit comprising a uid cylinder, a piston cylinder, a resilient seal interposed between these two cylinders and comprising a bottom portion whose area is equal to the internal cross-section of the uid cylinder, a continuous side wall in contact with the inner wall of the fluid cylinder, and a projecting iiange for clamping between adjacent portions of the fluid cylinder and piston cylinder, and a piston actuated by movements of the resilient seal, the piston comprising an end portion and a continuous side wall, the latter fitting snugly within the side wall of the resilient seal and the bottom portion of the piston conforming to and supporting the bottom portion of the resilient seal, the piston also having a .piston rod with a tapered end projecting beyond the piston cylinder, and a pair of thrust-imparting metal balls actuated by said tapered end, the tapered end being removable to substitute an end having a different taper.

5. A power unit provided with a cup-shaped resilient seal at an intermediate zone, a piston adapted to continuously support said resilient seal, a iiuid chamber to impart pressure against said resilient seal for actuation of the piston.

and a pair of thrust-imparting metal balls ac tuated by said tapered end.

2. A self-contained power unit comprising a fluid cylinder, a piston cylinder, a resilient seal 4 interposed between these two cylinders and comprising a bottom portion' whose area is equal to the internal cross-section of the nuid cylinder,

and means for actuating said power unit independently of said fluid means.

6. In a brake mechanism, the combination of brake shoes and a. power unit for actuating them, said power unit comprising a iiuid actuated piston terminating in a tapered piston rod, a tubular power head surrounding said piston rod, and a pair of hardened metal inserts mounted in a transverse aperture in said power head, whereby movement of said piston rod separates said metal inserts and actuates the brake shoes.

JESSE G. HAWLEY. 

